Michael Crichton’s State of Confusion

December 13th, 2004 by gavin

A central issue in the book concerns sea-level rise. Vanuatu is singled out for special attention since the islanders there are understandably concerned about their low-lying islands eventually being swamped. Sea level however is a surprisingly difficult thing to measure. Tide gauges are very noisy, and are usually located on the continental coast. Global trends in sea level from these gauges are between 1.7 to 2.4 mm/yr. Sea level though is not rising everywhere. In Scandinavia the continents are still rebounding from the ice age and local sea level is receding. Satellite data (TOPEX/POSEIDON and JASON) can give a global picture, and indicate that although the global mean rise over recent years (2.8 mm/yr) is significantly larger than the longer term trend estimated from tide gauges, sea level change is actually very dynamic. There are many patterns of behaviour particularly in the Pacific, associated with El Nino variability – possibly related to Vanuatu’s lack of actual sea level rise over the last 40 years. Curiously, Crichton cites the higher satellite derived number to claim that the rate of sea level rise has not increased recently (“[Sea level is] rising faster, Satellites prove it”,”Actually they don’t”), p424. There are clearly some problems in comparing tide gauge and satellite data, and of course, satellites can have their problems (cf. MSU data), but the quoted numbers don’t support the actual statement at all – though it would be fairer to say that the satellites are consistent with a recent rise in the rate, rather than a proof that it is occurring.

There are only a few out-and-out errors, but to be generous, they probably just slipped through the editing process. For instance, on p187 “higher temperature means more water vapor in the air and therefore fewer clouds” – Presumably, he meant that if the temperature is higher, the relatively humidity could be lower (and so there might be less clouds). On p368. “Croplands are warmer than forested lands”. This is probably a confusion with the urban heating issue, but the actual impact is the opposite – croplands have a higher albedo than forests, reflect more solar radiation, and are thus cooler. In fact, while this is not yet fully quantified, it appears to have been a significant cooling term in the global budget over the last 150 years. On p461 “…Greenland shows that, in the last hundred thousand years, there have been four abrupt climate change events” More like 40. And that is probably an undercount given that Greenland may not record events in the tropics.

At the end of the book, Crichton gives us an author’s message. In it, he re-iterates the main points of his thesis, that there are some who go too far to drum up support (and I have some sympathy with this), and that because we don’t know everything, we actually know nothing (here, I beg to differ). He also gives us his estimate, ~0.8 C for the global warming that will occur over the next century and claims that, since models differ by 400% in their estimates, his guess is as good as theirs. This is not true. The current batch of models have a mean climate sensitivity of about 3 C to doubled CO2 (and range between 2.5 and 4.0 degrees) (Paris meeting of IPCC, July 2004) , i.e an uncertainty of about 30%. As discussed above, the biggest uncertainties about the future are the economics, technology and rate of development going forward. The main cause of the spread in the widely quoted 1.5 to 5.8 C range of temperature projections for 2100 in IPCC is actually the different scenarios used. For lack of better information, if we (incorrectly) assume all the scenarios are equally probable, the error around the mean of 3.6 degrees is about 60%, not 400%. Crichton also suggests that most of his 0.8 C warming will be due to land use changes. That is actually extremely unlikely since land use change globally is a cooling effect (as discussed above). Physically-based simulations are actually better than just guessing.

Finally, in an appendix, Crichton uses a rather curious train of logic to compare global warming to the 19th Century eugenics movement. He argues, that since eugenics was studied in prestigious universities and supported by charitable foundations, and now, so is global warming, they must somehow be related. Presumably, the author doesn’t actually believe that foundation-supported academic research ipso facto is evil and mis-guided, but that is an impression that is left.